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Tough, unwanted plants can be difficult to battle
By Bonnie Coblentz
MISSISSIPPI STATE -- Certain weeds and invasive plants make gardening and yard maintenance a challenge to many Mississippians who share their property with troublesome plants.
Bamboo, poison ivy, kudzu, lawn burweed, Virginia buttonweed, Florida betony, Virginia creeper and leaf flower are among the unwanted plants that appear in Mississippi flower beds and yards. Some have thorns, some create rashes, others have poisonous berries, and most are invasive.
John Byrd, weed specialist with the Mississippi State University Extension Service, said controlling these plants is harder in flower beds and vegetable gardens than it is in lawns.
“These gardens frequently have a mixture of plant materials, and it's hard to find a herbicide to which your plants have widespread tolerance,” Byrd said. “Some chemicals that work well are available to commercial applicators, but not to homeowners.”
Many gardeners try to control these problem weeds by pulling them up by hand, but Byrd said this often breaks off part of the plant underground, leaving roots to come back in time. Herbicides tend to have a higher success rate as the chemical translocates, or moves from where it was applied through the plant, including the roots.
“For flower beds and some vegetable gardens, the best approach is to use a combination of hand weeding, mulching and selective chemical application,” Byrd said.
When using herbicides in tight areas, consider painting the solution on leaves with a paintbrush. Byrd said another trick is to wear a larger pair of absorbent cotton gloves over chemical-proof gloves. Dip the layered gloves in the chemical, and wipe the plant with the cotton gloves. The rubber gloves protect the gardener's hands from chemical exposure.
Wayne Wells, Extension turf specialist, said bamboo is tough to remove since it has a deep root system with rhizomes. Glyphosate, often sold as Roundup, works on the very small shoots, but not on mature canes that can grow as much as a foot a day.
“Cut down the mature canes and treat the small shoots with glyphosate when they pop up,” Wells said. “Try to remove as much of the underground root system as possible using tillers and shovels to expose the root system nodes that can grow more bamboo shoots.”
He said harsh chemicals such as Spike or Velpar will kill bamboo, but they may also kill everything else growing in the area. The residue stays in the soil for a long time and can kill desirable trees and other plants that are too close to the treated area.
Glyphosate controls poison ivy, as does dicamba and other hormonal-type herbicides such as 2,4-D. Use dicamba, 2,4-D or one of the sulfonyl-urea chemicals such as metsulfuron to control kudzu.
Lawn burweeds are winter annuals that establish stickers that can be dangerous to pets and bare feet.
“The best application is prevention, not control,” Wells said. “Apply a pre-emergence herbicide in late summer or early fall. If you miss this window, a lot of the post-emergence herbicides can kill them if applied by March 1. If you wait later when the burrs are developed, you may kill the plant, but the stickers will remain.”
Virginia buttonweed is a low-lying, very invasive weed with small white flowers and a long, oval-shaped leaf. It thrives in wet locations and can become very invasive in lawns. Sulfonyl-urea or hormonal products offer the best control.
The specialists cautioned homeowners that battling these weeds is rarely a one-time event. The plants will reappear until the roots are completely killed or removed. The specialists also cautioned homeowners to read herbicide labels completely and use only according to the labeling, as many of these products can move off target under various conditions.
The Extension Service publication 1532, Weed Control Guidelines for Mississippi, is available online or from any county Extension office.